CN-121993135-A - Acid fracturing method of ultra-deep high-temperature high-fracture-pressure carbonate reservoir

CN121993135ACN 121993135 ACN121993135 ACN 121993135ACN-121993135-A

Abstract

The invention discloses an acid fracturing method of a carbonate reservoir with ultra-deep high temperature and high fracture pressure, and relates to the technical field of reservoir reconstruction; the method comprises the following steps of predicting the fracture pressure profile to provide a basis for construction pump pressure, predicting the acidification scale and the displacement to provide a basis for acid pressure construction quantity, adopting an oil pipe to positively reduce the rock damage of the acid soaking perforation section to reduce the fracture pressure of the stratum, recycling clear water repeatedly for a plurality of times, replacing a heavy hydraulic reservoir, pumping a main acid liquid system and performing over-displacement operation, and can effectively reduce the acid pressure construction difficulty, reduce underground complexity, improve the construction success rate, shorten the construction period, save the construction cost and improve the reservoir transformation effect.

Inventors

Hu Qiujun
CHEN WEIHUA
LI LI
WANG HANCHENG
HU JINYU
TANG XINYUAN

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241105

Claims (11)

1. An acid fracturing method of a carbonate reservoir with ultra-deep high temperature and high fracture pressure is characterized by comprising the following steps: The fracture pressure profile prediction provides basis for construction pump pressure; the acidification scale and discharge capacity are predicted, so that a basis is provided for the construction quantity of acid pressure; rock injury treatment is carried out by adopting an oil pipe positive substitution acid breaking soaking perforation section to reduce the formation breaking pressure, and then clear water is recycled repeatedly; replacing the weighted hydraulic reservoir; Pumping a main acid liquor system; and (5) performing over-displacement operation.
2. The acid fracturing method of the ultra-deep high-temperature high-fracture-pressure carbonate reservoir according to claim 1, wherein the acid fracturing construction string is a reversible acid construction string.
3. The method of acid fracturing a carbonate reservoir at ultra-deep high temperature and high fracture pressure of claim 2 wherein the construction string comprises an oil tube assembly, a reversible and a positive packer connected to the oil tube assembly, and a perforating gun assembly connected to an end of the oil tube assembly.
4. The acid fracturing method of an ultra-deep high temperature high fracture pressure carbonate reservoir according to claim 1, wherein the acid fracturing reduction comprises the following components in percentage by mass: 15.0-20.0% of hydrochloric acid, 5.0-8.0% of organic acid, 2.0-4.0% of iron ion stabilizer, 2.0-4.0% of corrosion inhibitor, 0.5-2.0% of corrosion inhibition synergist, 1.0-1.5% of cleanup additive, 1.0-1.5% of clay stabilizer and the balance of clean water.
5. The acid fracturing method of an ultra-deep high-fracture-pressure carbonate reservoir according to claim 1, wherein the weighting fluid comprises the following components in percentage by mass: 60% -85% of clear water, 0.2% -1.0% of deoxidizer, 0.2% -1.0% of corrosion inhibitor, 5.0% -10.0% of HWJZ weighting agent and the balance of clear water.
6. The acid fracturing method of the ultra-deep high-temperature high-fracture-pressure carbonate reservoir according to claim 1, wherein the main acid liquid system is low-viscosity acid and comprises the following components in percentage by mass: 15.0-20.0% of hydrochloric acid, 3.0-5.0% of corrosion inhibitor, 0.5-1.0% of corrosion inhibition synergist A, 1.0-1.5% of corrosion inhibition synergist B, 2% -3.0 of iron ion stabilizer, 1.0-1.5% of cleanup additive, 1.0-1.5% of clay stabilizer, 0.1-0.5% of gelling agent for acidification and the balance of clear water.
7. The method for acid fracturing a carbonate reservoir at ultra-deep high temperature and high fracture pressure of claim 1, wherein the method for scale of acidizing comprises: The total construction time is controlled within the corrosion failure time limit of the construction pipe column, and the upper limit of the acid liquor scale consumption is calculated according to the relation between the acidification operation time and the displacement.
8. The method for acid fracturing a carbonate reservoir at ultra-deep high temperature and high fracture pressure of claim 7, wherein said method for scale of acidizing comprises: according to the acid leaching rock strength experiment and the adjacent area high-pressure reservoir construction experience, the acid breaking construction scale is optimized; the consumption of the weighting liquid is based on the principle of pressing open the reservoir, and the bottom hole pressure is calculated to be higher than the formation fracture pressure after acid damage; and obtaining an economic optimal scale range required by the target seam length through capacity simulation, optimizing the relationship of the half length of the seam and the half lengths of the seam under different construction scale conditions, and obtaining the low-viscosity acid construction scale by combining the construction time limit.
9. The acid fracturing method of an ultra-deep high temperature high fracture pressure carbonate reservoir of claim 1, wherein said displacement prediction method comprises: And selecting an acid absorption pressure gradient according to data such as drilling fluid density, formation pressure coefficient, horizontal minimum main stress gradient and the like, and predicting construction pump pressure under different acid absorption pressure gradients by combining wellhead pressure limiting, namely, the construction pump pressure=the acid absorption pressure gradient under different displacement, the bottom-hole vertical depth and the column friction-liquid column pressure under different displacement, so that the construction displacement is improved as much as possible under the condition of not exceeding wellhead pressure limiting.
10. The method for acid fracturing a carbonate reservoir at ultra-deep high temperature and high fracture pressure according to claim 1, wherein the method for reducing the fracture pressure of the stratum by rock injury treatment with the positive displacement of the acid-fracturing-soak perforation section of the oil pipe comprises the following steps: firstly adopting normal circulation of acid reducing and breaking to replace the acid reducing and breaking to be below a packer, standing for 20-40min, and then adopting reverse circulation of clear water to push the acid entering the annular air reducing and breaking device back into an oil pipe; Adopting acid reducing and clear water, repeatedly soaking and flushing perforation holes through forward circulation and reverse circulation, removing solid blocking particles near the perforation holes, and degrading the mechanical strength of rock through chemical reaction of acid liquor and rock; After repeated soaking and flushing, the acid reducing and breaking in the oil pipe is replaced by clear water.
11. The acid fracturing method of an ultra-deep high temperature high fracture pressure carbonate reservoir of claim 1, wherein said fracture pressure profile prediction method comprises: Rock mechanics and ground stress experiments are carried out by acquiring a rock core, young modulus, poisson ratio, horizontal minimum main stress and horizontal maximum main stress data are acquired, the fracture pressure of a target horizon is calculated by combining a fracture pressure empirical formula, ground stress data of strata with different depths are calculated by combining longitudinal and transverse acoustic wave time differences and densities of original logging data, and finally fracture pressure values with different well depths are obtained.

Description

Acid fracturing method of ultra-deep high-temperature high-fracture-pressure carbonate reservoir Technical Field The invention relates to the technical field of reservoir transformation, in particular to an acid fracturing method of a carbonate reservoir with ultra-deep high temperature and high fracture pressure. Background In recent years, with the increase of oil and gas exploration force, oil and gas exploration gradually breaks through to irregular, buried deep and abnormal high pressure directions, especially in carbonate rock reservoirs of ultra-deep wells, the reservoirs tend to be compact, the cracking pressure is ultra-high, slurry pollution, the stratum temperature is high and other complex environments, pumping pressure overpressure still cannot be generated in many exploration wells in engineering, and acid fracturing failure is caused by long-time retention of acid liquor in high-temperature environments, so that problems such as pipe column corrosion failure and the like are solved. In order to improve the acid fracturing success rate of the ultra-deep high-fracture-pressure reservoir, common solutions include ways of improving the pressure grade of wellhead devices and fracturing pipelines, reducing fracture by aggravated acid, deep perforation and the like, but for the ultra-deep high-pressure reservoir, the conventional pre-acid is not in direct contact with the stratum or the contact time is insufficient, so that the reservoir fracture pressure cannot be effectively reduced, a construction pipe column often does not have the capability of acid replacement after acid fracturing failure, the construction pipe column is influenced by long-time, high-temperature, high-pressure and acidic environments, packer channeling is carried out in the later stage of construction, long-time retention of acid causes pipe column corrosion failure to cause construction failure, the complex cost and period of treatment are increased, and the conventional pre-acid and aggravated acid are incompatible in the high-temperature environment to cause formation damage and influence the transformation effect. The patent document with the publication number of CN111946317B, named as an acid fracturing method of an ultra-deep, high-temperature and high-ground stress carbonate reservoir, adopts a heavy fracturing fluid to carry out test fracturing, adopts a gel fracturing fluid as a pre-fluid after fracturing, adopts cross-linking acid and the heavy gel fracturing fluid to carry out multistage alternate injection and expanding, and improves the fracturing and seam making effects. The patent does not consider the measure of directly contacting acid with stratum, can not effectively reduce the fracture pressure of the ultra-high stress reservoir, and does not consider the corrosion of acid liquor to the pipe column at high temperature, and the corrosion failure of the pipe column is caused by overlong construction time. The patent document with the publication number of CN115726753A, named as a fracturing modification method and application for ultra-deep high-stress reservoirs, adopts an equal-aperture perforation technology to reduce the fracturing pressure, adopts acid to pretreat a shaft and a blasthole, pumps liquid carbon dioxide, pumps low-viscosity slick water in a pulse-rise displacement mode, and solves the difficult problems of difficult fracturing and difficult seam expanding of the high-stress reservoirs. The problem of the reservoir can be solved by adopting carbon dioxide and low-viscosity slickwater to make the seam, but the construction risk is high by adopting carbon dioxide, and the diversion capacity of the carbonate reservoir can not be effectively improved by adopting slickwater to make the seam. Based on the above, an acid fracturing method of a carbonate reservoir with ultra-deep high temperature and high fracture pressure is provided. Disclosure of Invention The invention aims to overcome the problems in the prior art, and provides an acid fracturing method for a carbonate reservoir with ultra-deep high temperature and high fracture pressure, which can effectively reduce the difficulty of acid fracturing construction, reduce underground complexity, improve the construction success rate, shorten the construction period, save the construction cost and improve the reservoir reconstruction effect. The invention is realized by the following technical scheme: an acid fracturing method of a carbonate reservoir with ultra-deep high temperature and high fracture pressure comprises the following steps: The fracture pressure profile prediction provides basis for construction pump pressure; the acidification scale and discharge capacity are predicted, so that a basis is provided for the construction quantity of acid pressure; rock injury treatment is carried out by adopting an oil pipe positive substitution acid breaking soaking perforation section to reduce the formation breaking pressure, and then clear wat